# On Types

DevFeed: [On Types](<https://devfeed.tech/articles/on-types-21794.md>)

Original publisher: [Read original article](<http://blog.cleancoder.com/uncle-bob/2021/06/25/OnTypes.html>)

Published: 2021-06-25T00:00:00Z

Content type: article

Language: en

Sources: [Robert C. Martin](<https://devfeed.tech/sources/robert-c-martin.md>), [The Clean Code Blog](<https://devfeed.tech/sources/the-clean-code-blog.md>)

Topics: [Code](<https://devfeed.tech/topics/code.md>), [Assembly](<https://devfeed.tech/topics/assembly.md>), [Finite-state machine](<https://devfeed.tech/topics/finite-state-machine.md>), [IO](<https://devfeed.tech/topics/io.md>), [Operating system](<https://devfeed.tech/topics/operating-system.md>)

Tags: [code](<https://devfeed.tech/tags/code.md>), [ibm](<https://devfeed.tech/tags/ibm.md>), [io](<https://devfeed.tech/tags/io.md>), [memory](<https://devfeed.tech/tags/memory.md>), [program](<https://devfeed.tech/tags/program.md>), [state](<https://devfeed.tech/tags/state.md>)

## AI overview

An autobiographical account of early programming experiences from 1964 through the early 1970s, covering finite-state machines, binary machine language, assembly programming, magnetic-tape record processing, and programming on systems with limited memory and no operating system.

## Source excerpt

I wrote my first program in 1964. The name of the program was: Mr Patternson's Computerized Gate, and it was implemented on a little plastic computer named DIGICOMP-I, which was a cute little three bit finite state machine with 6 AND gates. The first electronic computer I ever wrote a program for was an ECP-18 in 1966. This was a 15 bit wide machine with 1024 words of drum memory. The programs I wrote were all in binary machine language and were entered through the front-panel switches. In the years between 1967 and 1969 my father would drive my friend, Tim Conrad, and I 25 miles to the Digital Equipment Corp sales office, where we would spend our Saturdays entering programs into the PDP-8 that they had on the floor. They were very gracious to allow us such access and freedom. The code we wrote was in PAL-D assembler (which was written by Ed Yourdon when he was 21 years old). My very first job as a programmer was temporary. A matter of two weeks. I was 17, and the year was 1969. My father went to the CEO of a nearby insurance actuarial firm, ASC Tabulating, and in his inimitable fashion, told them that they would be hiring me for a summer job. He had a way of being very convincing. The program I wrote for ASC was named IDSET. It was written in Honeywell H200 assembler (the language was called Easycoder and was based on IBM 1401 Autocoder). The purpose was to read student records from a magnetic tape and insert ID codes into those records, and then write them out onto a new tape. With some coaching, I was able to get that program to work. Upon graduating High School, in 1971, I got a job at ASC again; but this time as a third-shift off-line printer operator. We were printing junk mail, which was a brand new thing back then. A few months later I was hired as a full-time programmer analyst at ASC, and was assigned to work on huge re-write of a massive accounting and records system for Local 705 Trucker's union in Chicago. The existing system ran on a great big GE Datan